Nebulizers



Get. 21, 1969 N. N. URBANOWICZ NEBULIZERS 2 Sheets-Sheet 1 Filed June21, 1965 FIG. 4

FIG.3

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INVENTOR. NICK N. URBANOWICZ mmw ma ATTORN EYS Patented Oct. 21, 19693,473,530 NEBULIZERS Nick Nikodem Urbanowicz, 151 Albion St., Brantford,Ontario, Canada Filed June 21, 1965, Ser. No. 465,672 Int. Cl. A61m /00;A611 9/00; 1305b 3/14 US. Cl. 128194 7 Claims ABSTRACT OF THE DISCLOSUREA nebulizer characterized by a nebulizing action which is gained bypassing a carrier gas through a small aperture in a horizontallydisposed plate surface on which has been formed a thin film of theliquid or fine powder to be nebulized. The nebulization results from theturbulence in the carrier gas as it emerges from the aperture andturbulence can be increased by the use of a bafii'e placed immediatelyabove the aperture. A fine mesh screen may be placed on the platesurface to reduce surface tension in the film. Other embodiments employa diaphragm plate surface which is vibrated by the gas passing throughthe aperture and a liquid reservoir beneath the plate subjected to thegas pressure to feed liquid to the plate surface.

This invention relates to the manufacture of nebulizing devices and isparticularly concerned with a nebulizer which is not subject toclogging.

A nebulizer essentially consists of a device for atomizing liquids. Suchdevices have been used widely for many years as a means of creatingbeneficial atmospheres in sick rooms. In effect, the atmosphere breathedby a patient is used as a means for administering drugs throughinhalation.

The majority of nebulizers now available on the market operate on theprinciple wherein air or oxygen or other base gas is forced through aventuri throat and the liquid to be atomized is drawn upwardly through acapillary tube having its upper end positioned at the venturi throat.The disadvantage of this arrangement is that the capillary tubes oftenbecome clogged after varying periods of usage, either through a build-upof solids precipitated from the fluids being nebulized or impuritiesinadvertently included in the fluids. More often than not, it isimpossible to determine the likelihood of a blockage occurring in thecapillary tube in advance and it is occasionally found that a patientwho is supposed to be receiving medication through nebulization of thesurrounding atmosphere has not been receiving medication due to cloggingof the nebulizing device and this can on occasion have serious effectson the recovery of the patient. It is, therefore, most desirable incertain cases that nebulization be guaranteed.

A further disadvantage of the nebulizers now available is that they arecapable of nebulizing only liquids. There has been a recent trend to theprovision of extremely fine powders as medicants to be dispersed in theatmosphere. There are advantages to the dispersion of powders directlyinto the atmosphere as contrasted with first dissolving the powder in aliquid. Unfortunately, the presently available nebulizers are capable ofatomizing only liquids.

It is the chief object of this invention to provide a nebulizer whichdoes not employ the principle of passing the air through a venturithroat while drawing the liquid to be nebulized upwardly through acapillary tube as to avoid the danger of blockage of the tube.

It is a further object of the invention to provide a nebulizer which iscapable of atomizing powders as well as liquids.

It is a more specific object of the invention to provide a nebulizerwhich in its simplest form consists of a receptacle adapted to holdliquid to be nebulized, which receptacle includes a bottom wall havingat least one aperture extending therethrough and further including meansfor forcibly passing air or other carrier gas upwardly through theaperture whereby the gas picks up the substance to be nebulized at itemerges from the aperture.

The above and further objects of the invention will be understood fromthe following description of preferred embodiments thereof as read inconjunction with the accompanying drawings.

In drawings which illustrate these embodiments:

FIG. 1 is a frontal perspective view, partly broken away, of a nebulizerin accord with the simplest embodiment of the invention;

FIGS. 2, 3 and 4 are cross-sectional views taken along the verticalplane through modified forms of the nebulizer illustrated in FIG. 1;

FIG. 5 is a frontal perspective view, partly broken away, of a nebulizerin accord with a second embodiment of the invention;

FIG. 6 is a perspective view of a screen and an alternative diaphragmemployed in the embodiment of FIG. 5; and

FIG. 7 is a cross-sectional view taken through a vertical plane of afurther embodiment of the invention characterized by means forautomatically feeding liquid to be nebulized.

Referring to FIG. 1, the nebulizer in accord with this simplest form ofthe invention essentially consists of a receptacle 10 adapted to hold aquantity of liquid to be nebulized in which the receptacle includes abottom wall 12 having a single central aperture 14 extendingtherethrough and an air tube 16 connectible to a source of air underpressure and adapted to feed pressurized air upwardly through aperture14. The connection of tube 16 to the underside of wall 12 might beeffected by any one of a number of known ways. As illustrated, thisconnection is effected by enlarging the lower end of aperture 14,providing a female thread on the inside surface of this enlarged portionand providing a male threaded connector on the end of tube 16 and asuitable locking element such as 17. The wall of the receptacle ispreferably extended downwardly beneath the bottom wall 12 simply toprovide a footing for resting the nebulizer on a flat surface withoutinterference from tube 16.

The substance to be nebulized, which in the normal course will be liquidbut could also be a fine powder, can be fed into the receptacle in anyone of a number of ways. Thus, for example, a fluid feeding deviceoperating on the burette principle might be positioned above thenebulizer to drop liquid at regularly timed intervals through the openupper end of the receptacle onto bottom plate 12, preferably at such arate to maintain a relatively thin film of the liquid on the bottomplate. Alternatively, the liquid or powder to be nebulized may be fed ata predetermined rate through a separate feeding tube 18 rather thanthrough the open upper end of the receptacle.

It will be appreciated that nebulization of the liquid or powder restingon the upper surface of bottom plate 12, in the form of a thin filmthereof, takes place as the air or other carrier gas emerges fromaperture 14 with a certain amount of turbulence creating actionsufiicient to break up the liquid into extremely fine droplets which arethen carried by the air out through the open upper end of the nebulizerand into the surrounding atmosphere. In the case of powder, the actionis not a true nebulizing action as the word nebulizer implies breaking aliquid into fine particles whereas with a powder, the fine particlesalready exist and the action is largely one of creating turbulence as topick up the particles from a thin film thereof that has been formed onthe top surface of plate 12 so as to disperse the particles through thecarrier gas which will then carry particles into the surroundingatmosphere.

FIGS. 2, 3 and 4 show modified forms of the nebulizer illustrated inFIG. 1. These forms differ from one another primarily in the shape ofthe top surface of bottom wall 12. They are illustrated to emphasize thefact that the shape of this top surface is not critical, with theexception that extreme shapes such as those which would make itimpractical to feed the substance to be nebulized to the outlet orificeof aperture 14 at an even rate could not be used.

For the purposes of illustration, aperture 14 is shown in the drawingsmuch larger in diameter than would be actually employed in a bottomplate of the dimensions shown in the drawings. It is to be noted,however, that apart from the fact that the aperture must have a diameterno less than a certain practical minimum size, the diameter and even theshape of the outer orifice is large ly determined by such considerationsas the overall size of the nebulizer concerned, the nature of thesubstance being nebulized and the pressure under which the air or othercarrier gas is forced upwardly through the aperture. For all practicalpurposes, however, the minimum operative diameter of the aperture (morespecifically, the outlet orifice) is in the order of 0.0005 inch. It isalso to be noted that while the forms of the invention illustrated inFIGS. 1 to 4 all employ a single, centrally positioned aperture, two ormore apertures may be used provided, of course, that means is alsoemployed for forcibly feeding air or other carrier gas upwardly througheach of the apertures. In this regard, it is mentioned that in accordwith the invention, nebulization of a liquid or pickup of fine powderparticles is believed to be the result of turbulence created within theliquid or powder receptacle and with certain liquids or powders, theproper amount of turbulence might be better effected by the use of aplurality of apertures rather than the single aperture illustrated.

The embodiment of the invention illustrated in FIG. employs severalrefinements on the simple form of the invention illustrated in thepreceding figures. In this case, the receptacle is formed of two parts,namely a base 20 on which an upstanding cylindrical part 22 is removablyfixed as by the use of holding screws 24. One advantage of thistwo-piece arrangement is that the bottom wall, which in this case takesthe form of a thin metal membrane, may be readily removed from thenebulizer for cleaning or replacement. Thus, for example, it might bedesired to change the bottom wall from one having a single aperture suchas shown in FIG. 5 to one having a plurality of apertures such as shownin FIG. 6.

In using the membrane type of replaceable bottom wall, as shown in FIGS.5 and 6, it is not practical to directly connect the air feeding tube 16to the underside of the bottom wall. Accordingly, the lower half 20 ofthe receptacle is provided with an air chamber 28, with the tube 16being connected to chamber 28 through a vertical bore 30 and ahorizontal bore 32 in the lower end of portion 20. With the use of anair chamber and a relatively thin bottom wall 26, it has been found thatas the air is forced under pressure upwardly through the aperture in thewall, the latter is caused to vibrate at a very high frequency. It isbelieved that this action assists in both urging the liquid to benebulized across the top surface of the bottom wall towards the apertureand in creating additional turbulence to assist break-up of the liquidinto fine droplets. It is also found that movement of the liquid towardsthe aperture is assisted by the use of a fine mesh screen 34 on top ofthe bottom wall. It is believed that the effect of this screen is tobreak up surface tension between the thin film of fluid being nebulizedand the top surface of the bottom wall which can have the tendency toretard movement of the fluid towards the aperture or apertures. Screen34 is also held in place between the lower edge of the top portion ofthe receptacle and the mating portion of the lower part 20. Aspreviously mentioned, the two parts of the receptacle can be separatedwhich also provides access to the screen as well as the bottom wall 26for cleaning or replacement. The screens illustrated in both FIGS. 5 and6- are provided with a central slot 36 to expose the aperture orapertures. In fact, any suitably shaped opening in the screen may beused, it only being required that the egress of air from the upperorifice of the aperture should not be interfered with by the screen.

The embodiment of the invention shown in FIG. 5 further differs from thesimpler form of the invention illustrated in FIGS. 1 to 4 in the use ofa baffie 38 which is positioned above but somewhat spaced from theoutlet orifice of the aperture. The use of such a battle is a preferredexpedient as it has been found that more often than not improvednebulization will be gained by the use of a baffle which is believed tohave the elfect of providing additional turbulence within the lower endof the fluid holding receptacle. Baffles of various shapes and sizeshave been successfully employed and it does appear that the actual shapeof the baffle is not critical, provided the selected shape doesaccomplish the desired creation of additional turbulence. The bafileillustrated simply consists of a rod-like member which extends acrossthe lower end of the receptacle directly above the aperture. The rodmight be made of any one of a different number of materials but, as withall the materials used in the nebulizer, it should be of a materialcapable of being cleaned, having in mind the ultimate purpose of thenebulizer which is to provide beneficial atmospheres to be breathed byhospital and other sickroom patients. Thus, for example the baflie wouldpreferably be manufactured of glass, stainless steel or a hard plastic.As illustrated, bafile 38 is held in position by means of a pair ofscrews 40 which hold the ends of the bafile against the underside of aflange 42 carried on the inside surface of the wall of receptacle 22.However, it will be appreciated that various alternative means might beemployed for mounting the bafile at the desired position. Further, thebaflie may be mounted in such a way to permit adjustment of its heightabove the aperture. In using a diaphragm type bottom wall such as themember 26a shown in FIG. 6 and having a plurality of apertures, thebaflle would be properly oriented as to be positioned above each of theapertures. Similarly, in using a bottom wall having a number ofapertures which are not necessarily arranged along a single line, thebaffle means employed will be shaped and sized as to be positioned overeach of the apertures. It has been found that the actual size of thebaflie is not critical, although it will be appreciated that a bafiiewhich is so large as to virtually block off upward flow of air emergingfrom the aperture or apertures would not be acceptable. Thus,, it hasbeen found that, generally speaking, the lateral dimension of the baflierelative to the size of the aperture should not exceed a ratio ofapproximately 7 to 1. The term lateral dimension could have differentinterpretations depending upon the shape of the bafile concerned and inthe case of a rod-like baflle, such as the one illustrated in FIG. 5, itis the diameter of the rod which would be described as the lateraldimension. Should the baflle selected comprise a square plate, thelateral dimension would be the same as the length dimension. Generallyspeaking, therefore, the lateral dimension will constitute the smallestdimension impeding upward flow of air emerging from the aperture overwhich the batfie is positioned.

Referring now to FIG. 7, the nebulizer according to this embodiment ofthe invention incorporates features of the previously describedembodiment and is characterized by means wherein the liquid to benebulized is automatically fed to the top surface of the bottom wall ofthe receptacle. To this end, the receptacle 20 is attached at its lowerend to a fluid container 50 through any type of fluid-tight connectionsuch as the threaded connection illustrated. A feeding tube extendsthrough bottom wall 52 of receptacle 2t} and extends downwardly to apoint close to the lower end of container 50.

As will be readily appreciated from FIG. 7, feeding of the liquidcontained in container 50 is elfected through the build-up of airpressure on the top surface of the contained liquid which forces theliquid upwardly through tube 51 onto the top surface of botom plate 52.The chief advantage of this arrangement is that no separate liquidfeeding arrangement is required and the same air pressure which is usedto force air upwardly through the aperture in bottom plate 52 is used tofeed the liquid onto the surface of this bottom plate. Thus, it can beseen that the rate of nebulization can be effectively controlled simplyby varying the air pressure. To vary the rate of nebulization with thepreviously described embodiments, both the air pressure forcing airupwardly through the aperture and the rate at which liquid is fed ontothe top surface of the bottom plate of the receptacle must be separatelycontrolled. This has the disadvantage that if the feeding rate of theliquid is not stepped down at the same rate as the reduction in airpressure, an excessive build-up of liquid on top of the bottom plate islikely to occur. On the other hand, the embodiment of FIG. 7 is notadapted to the pick-up of powders as are the embodiments of the FIGS. 1to 6. Should additional control of the feeding rate of the liquid berequired in the FIG. 7 embodiment, a needle valve control 54 may beattached to the upper end of tube 51.

FIG. 7 shows one additional feautre which might also be adapted in theembodiments of the other figures of the drawings. This is the shaping ofthe outer edge of bottom plate 52 so that the latter is curved upwardly.It has been found that under certain circumstances, this particularshaping of the lower end of the receptacle aids in creating turbulentfiow through the setting up of eddy currents within the lower end of thereceptacle.

Nebulizing devices in accord with this invention have the advantage ofsimplicity which makes the devices relatively inexpensive to manufactureas compared with nebulizing devices heretofore available. Mostimportant, however, is the fact that this simplicity of construction andoperation renders the devices of the invention virtually fool-proof inoperation. Specifically, the devices are not subject to clogging whichhas been a chief drawback of the nebulizing devices operating on theprinciple wherein the substance to be nebulized is drawn upwardlythrough a capillary tube which terminates at a venturi throat throughwhich the carrier gas is passed. Further, of course, the nebulizingdevice of two embodiments of this invention are adapted to pick up finepowders so that their utility is not restricted to the nebulization ofliquids.

What I claim as my invention is:

1. A nebulizer comprising a receptacle adapted to hold a quantity of asubstance to be nebulized, said receptacle including a bottom wall whichextends substantially horizontally when the nebulizer is arranged in itsnormal operative position, whereby said bottom wall is adapted for theformation and retention thereon of a. thin film of said substance to benebulized, means for forming a thin film of the substance to benebulized on the top surface of said wall, an aperture extending throughsaid bottom wall, turbulence inducing bafile means positioned above theoutlet orifice of said aperture, means carried by said nebulizer andconnectible to a source of pressurized carrier gas for directing carriergas upwardly through said aperture whereby said carrier gas picks upsaid substance, from a thin film thereof that has been formed andretained on said bottom wall, as it emerges from the outlet orifice ofsaid aperture, said receptacle further including outlet means for theegress of the resultant mixture of carrier gas and nebulized substance.

2. A nebulizer as claimed in claim 1, in which the ratio of the minimumlateral dimension of said baffle to the cross-sectional dimension of theoutlet orifice of said aperture is less than 7 to 1.

3. A nebulizer as claimed in claim 2, in which the outlet orifice ofsaid aperture has a minimum crosssectional dimension of 0.0005 inch.

4. A nebulizer comprising a receptacle adapted to hold a quantity of asubstance to be nebulized, said receptacle including a membrane-likebottom wall which extends substantially horizontally when the nebulizeris in its normal operative position, whereby said bottom wall is adaptedfor the formation and retention thereon of a thin film of said substanceto be nebulized, means for forming a thin film of the substance to benebulized on the top surface of said wall, a fine mesh screen positionedon the top surface of said bottom wall for reducing surface tensionbetween a liquid substance to be nebulized and the top surface of saidbottom wall, said receptacle further including a chamber beneath saidbottom wall; means for connecting the interior of said chamber with asource of pressurized carrier gas; an aperture in the center of saidmembrane-like bottom wall having a lower inlet orifice in fluidcommunication with said chamber and an upper outlet orifice wherebycarrier gas forced into said chamber under pressure passes upwardlythrough said aperture and picks up the substance to be nebulized, from athin film thereof that has been formed and retained on said bottom wall,as it emerges from said outlet orifice of said aperture, a rod-liketurbulence creating baffie means positioned above the outlet orifice ofsaid aperture, said receptacle further including outlet means for theegress of the resultant mixture of said carrier gas and said nebulizedsubstance.

5. A nebulizer as claimed in claim 4, in which said receptacle is formedof two parts removably connected together along a parting linesubstantially corresponding to the plane of said bottom wall and inwhich both said bottom wall and said screen are held in position byengagement of their outer edges between said two parts of thereceptacle.

6. A nebulizer as claimed in claim 5, in which said bottom wall has aplurality of apertures.

7. A nebulizer as claimed in claim 6, in which said plurality ofapertures are arranged along a line and in which said rod-like baflle ispositioned above and spaced from the outlet orifices of all of saidapertures.

References Cited UNITED STATES PATENTS 3,105,104 9/1963 Neiss 128-l86 XR3,189,405 6/1965 Fulton et a1. 21-121 3,206,124 9/ 1965 Drayer et a1239-4 XR FOREIGN PATENTS 1,147,355 4/ 1963 Germany.

WILLIAM E. KAMM, Primary Examiner US. Cl. X.R.

